Female mice can be turned "lesbian" by deleting a single gene at
embryo stage, scientists have discovered.

The simple procedure causes the modified mice to reject the advances of their male counterparts and attempt to mate with fellow females.

Researchers found that disabling the FucM gene – which influences the levels of oestrogen to which the brain is exposed – caused the mice to behave as if they were male as they grew up.

Professor Chankyu Park of the Korea Advanced Institute of Science and Technology in Daejon, South Korea, who led the research, said: "The mutant female mouse underwent a slightly altered developmental programme in the brain to resemble the male brain in terms of sexual preference."

Scientists have long sought a genetic link to homosexuality, but the academics behind the latest study stressed that it was impossible to say whether their discovery had any relevance to human sexuality.

By deleting the enzyme-producing gene, the scientists believe that they caused the female mice to be exposed to extra oestrogen, by preventing their brains from filtering out the hormone.

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While oestrogen masculinises the brain in mice, it does not have the same effect on humans.

Professor Park now hopes to investigate whether the enzyme produced by the gene – fucose mutarotase – has any influence on human sexuality, but conceded that it may be "very difficult" to find willing volunteers.

His most recent findings have been published in the BMC Genetics journal.